The present invention relates generally to ultrasound imaging, and more particularly to an imaging method and system based on the interaction of ultrasound pulses with a static magnetic field, preferably used to image the human body.
Conventional ultrasound imaging techniques rely essentially only on the acoustic properties of the object or subject being imaged as the basic contrast mechanism for producing an image. Specifically, in such conventional ultrasonic imaging the progression of the pulse is monitored by detecting the echoes of the pulse reflected back at the tissuexe2x80x94tissue interfaces, and is therefore entirely a characterization of the acoustic impedances of the tissues. The acoustic path involved starts from the transducer that generates the ultrasonic pulse, reaches the tissuexe2x80x94tissue interfaces, and back to the transducer if it is also used to receive the echoes, or to another receiving transducer. The overall efficacy of such conventional ultrasound techniques is often hindered by the limited sizes of the acoustic windows in the body. Moreover, there is an inherent problem of beam expansion and low angular resolution away from the origin of the beam in these conventional ultrasound imaging methods.
Thus, although conventional ultrasound techniques provide a very useful imaging modality, further advancements in ultrasound techniques would be advantageous, particularly to provide an improved ultrasound-based imaging method which is not limited to contrast based solely on acoustic impedance, is not limited by beam expansion, and is not limited by the sizes of acoustic windows.
It is, therefore, an object of the present invention to provide a new ultrasound-based imaging modality.
A related object of the present invention is to provide a new ultrasound-based imaging modality that is based on the interaction among a static magnetic field and conductive moieties or media having a motion or displacement that is associated with acoustic energy.
Another object of the present invention is to provide a new ultrasound-based imaging modality that provides a contrast mechanism which includes the conductivity of the medium being imaged.
The present invention achieves these and other objects, and overcomes the above mentioned and other limitations of the prior art, by providing a method and system for imaging a subject or object having conductive properties, such that a static magnetic field is applied to the object or subject, and an ultrasound pulse is propagated into the object, and an electrical signal is detected which is related to the interaction of the ultrasound pulse local displacement of the conductive object and the magnetic field. Alternatively, and equivalently, a static magnetic field is applied to the object or subject, an electrical pulse is propagated into the object, and an ultrasound signal is detected which is related to the interaction of the electrical pulse generated in the conductive object and the magnetic field. The acquired acoustic signals or the acquired electrical signals are processed to provide an image of the object. The acquired signals are dependent on local conductivity as well as local acoustic properties. Imaging in accordance with the present invention is hereinafter also referred to as ultrasound-Hall effect imaging or Hall effect imaging (HEI).